A. Field of Invention
This invention pertains to implantable devices used to provide various types of therapy, and more particularly, to such devices having protection means from high energy ambient electrical interference such as electrostatic discharge (ESD).
B. Description of the Prior Art
Implantable electronic devices are used to provide therapy to patients suffering from a wide range of health problems. For example, cochlear devices are used to aid people suffering acute loss of hearing. Pacemakers and cardioversion/defibrillation devices are used to aid patients with cardiac arrhythmias.
Since these devices, when implanted, are immersed in fluids which are highly electrolytic and, since they are provided in an electrically conductive casing, one would expect that they would be well shielded from ambient electrical interference. In fact, a very large number of such devices have been implanted and in use for the last twenty years and the number of failures attributed to any ambient electrical interference has been minimal. However, there has been a small number of instances known to the inventors where cochlear implants have failed, apparently due to high energy level ambient electromagnetic fields.
Thus, it appears that there is a need for improving the protection of implantable devices from ambient electromagnetic interference. Moreover, since a large number of such devices have already been implanted, it would be beneficial to have a means of increasing the protection of the implanted devices in a manner which does not require explantation.